1. Field of the Invention
This invention relates generally to flexible hose couplings. More particularly, it relates to a novel and improved quick connect hose coupling.
2. Description of the Prior Art
Quick connect couplings are known. In such a coupling, a port may be machined directly into an associated fixture, machinery or equipment, or a body assembly or fixture portion may have the port and threads for pre-assembly on an associated fixture, machinery or equipment. The hose connection portion, including a hose stem portion and a ferrule, is attached to an open end of the hose to be connected to the fixture, machinery or equipment. The hose stem portion has a hose insert portion, which is inserted into the open end of the hose. The ferrule is then compressed about the hose end containing the insert causing all portions to be permanently affixed. Merely pressing the hose connection portion into the port subsequently completes the hose connection. Such a quick connect coupling is particularly desirable when the hose must be connected in a location which is not readily accessible, since it eliminates the need for starting the threads and the danger of cross threading. Further, for such a coupling having its port included in a body assembly or fixture portion, it may be threaded into place as a pre-assembly operation making it easy to insure that the body assembly or fixture portion receives proper torque. Further, the time of assembly and assembly costs are reduced.
A quick connect coupling can be provided without a disconnection mechanism, such as where the port is machined directly into the fixture, machine, or equipment without an additional provision for disconnection. However, for a quick connect coupling having its port integral to a body assembly or fixture portion, the disconnection includes unscrewing all or a portion of the body assembly or fixture portion from the machine or fixture to which their respective hose is attached.
Where the body assembly or fixture portion is unitary, the entire body assembly is unscrewed from the machine or fixture. The body assembly or fixture portion can also include intermediate threads making it separable into pieces, usually a draw-down nut portion having the quick connect feature and an adapter having the bore which corresponds to the male connection portion of the hose stem. Upon unthreading the threaded portion, one part of the body assembly remains with the machine or fixture. The other part separates from the first part and remains with the hose connection portion. In either instance, while connection is a quick single stroke process, the disconnection requires a slower unthreading process to provide the opportunity to discover that the fitting is under internal pressure before being completely disconnected. Reconnection is effected, from this point forward, by the inverse of the disconnection process.
Quick connect couplings provide means to seal between the hose stem and the port and to provide a mechanical locking of the hose stem in the port. To achieve maximum benefit from a quick connect coupling, such a coupling must reliably connect under the adverse conditions encountered such as in industrial or heavy machinery locations, where installations of fluid connections are numerous, dense, and almost inaccessible. Characteristics that are important to ensure that a quick connect coupling reliably connect include: 1) the required insertion force of the coupling being low; 2) the required insertion force being consistent among sibling couplings; 3) the coupling being axially self-aligning; 4) the coupling being highly resistive to binding upon misaligned insertion of the stem into the port; 5) the coupling being self guiding to overcome substantial lateral misalignment when the process of connection is first begun; and, 6) the coupling being highly resistive to binding upon misalignment of stem in relation to the clip upon insertion of the stem into the port. Still, the hose stem portion must seat securely upon completion of connection, and should result in a stable and durable connection.
One approach toward obtaining the characteristic of the coupling being highly resistive to binding upon misalignment of stem in relation to the clip upon insertion of the stem into the port is found in U.S. Pat. No. 4,565,392 to Vyse. The issue is described in Vyse '392 as follows: “A problem that has been encountered in making this connection is that, at the time the [stem] is pushed into the socket, the forward end of the [stem] sometimes jams or catches on the snap ring which is mounted in the interior opening of the [port]”. The jamming that is being described is where the snap-ring is forced out of the interior opening, or snap-ring groove, and deeper within the port by the stem pressing upon only a small portion of the snap-ring (as opposed to uniformly about the snap-ring), causing it to tilt and thereby clog the port. The clog prevents the stem from being allowed to seat fully within the port to a point of locking into place, or forming an axial locking relationship between the stem and port.
The solution presented by Vyse '392 was to fill the snap-ring groove, in which the snap-ring would reside prior to connection of the coupling, with a viscous fluid such as grease, to maintain a centered position for the snap-ring at all times prior to the insertion of the stem in the port. In this way the snap-ring is not allowed to be pulled from a centered position within the groove by gravity. As long as the ring is centered, the opportunity for the stem to catch the ring and force it to tilt within the port is apparently reduced. However, the solution presented by the Vyse '392 patent has a significant disadvantage and limitation. It is very undesirable to introduce grease to the coupling in the manner described. It requires a manual step in the production of the coupling, adding cost and complexity. More significantly, the grease represents contamination that can interfere with proper functioning of the coupling over its life and acts to hold other contaminants within the coupling, such as particulates that can be very abrasive. While, the grease may be effective at securing the clip against movement by gravity, it does not insure that the clip will not be moved out of proper placement by handling or bumping of the port any time prior to connection. When the clip is moved by handling or bumping, the grease only insures that the clip remains in any position it assumes, whether proper or not.
The use of grease by the Vyse '392 patent does not address the other important characteristics of 1) the required insertion force of the coupling being low; 2) the required insertion force being consistent among sibling couplings; 3) the coupling being axially self-aligning; 4) the coupling being highly resistive to binding upon misaligned insertion of the stem into the port; and, 5) the coupling being self guiding to overcome substantial lateral misalignment when the process of connection is first begun.
Accordingly, there is a continuing need for a hose coupling that achieves all six of these important characteristics.